INTRAARTERIAL PHOTODYNAMIC THERAPY USING 5-ALA IN A SWINE MODEL

Objectives: to test the hypothesis that intravascular light could be d elivered via a balloon catheter for arterial photodynamic therapy (PDT ). Design: pig non-injury model. Materials: clinical catheter equipmen t. Methods: large White pigs (15-20 mu g) were photosensitised with 5- aminolaevulinic acid (5-ALA) induced protoporphyrin IC (PpIX) at a con centration of 120 mg/kg. Arterial biopsies were taken at intervals bet ween 30 mins and 24 h and frozen sections analysed using a CCD camera to give a temporal profile of fluorescence in each arterial layer. PDT was given to normal arterial segments via a 4 mm transparent PTA ball oon inflated so as to occlude flow, but not distend the artery. Animal s were culled at 3 and 4 days and the above segments harvested. Result s: fluorescence peaked in the adventitia, intima and medial layers at 1.5, 4 and 6 h respectively. PDT at all time points produced VSMC depl etion compared wi controls. The degree of depletion mirrored the fluor escence profile of PpIX. Conclusions: PDT can be delivered via a stand ard PTA balloon with a transparent channel. This depletes the VSMC pop ulation within the arterial wall without complications. Intra-arterial PDT is therefore a potential therapy to reduce the incidence of reste nosis post-angioplasty.